Xen Project Developer Summit

Storage systems continue to deliver better performance year after year. High performance solutions are now available off-the-shelf, allowing users to boost their servers with drives capable of achieving several GB/s worth of throughput per host. To fully utilise such devices, workloads with large queue depths are often necessary. In virtual environments, this translates into aggregate workloads coming from multiple virtual machines.
Having previously addressed the impact of low latency devices in virtualised platforms, we are now aiming at optimising aggregate workloads. We will discuss the existing memory grant technologies available in Xen and compare trade-offs and performance implications of each: grant mapping, persistent grants and grant copy. For the first time, we will present grant copy as an alternative and show measurements over 7 GB/s, maxing out a set of local SSDs.